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Does anyone know how to remove this crank arm? Or if it can be removed? The bike was ~$250 and seems to have a lot of 'don't take this apart' engineering, I'd like to soak the chain rings in rust remover without the arm interfering. The interface is also just a bit loose. It's not clear if there's any way to tighten that gear-looking around the square.

Chain ring

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    There's not enough rust there to make it worth disassembling. Instead, apply some rust refixer like Phosphoric Acid (like "rustbuster") and then keep riding. The teeth look fine, so if you're getting transmission problems its time for a new chain and cassette. – Criggie Jun 23 '17 at 0:26
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    There's not much point as @Criggie says. To get that apart you'd need a load of heat and or a press. The heat would mess up the paint work and probably warp the chain rings if you got it wrong. I'd personally clean it off with some degreaser and some wet-n-dry sandpaper if the rust is bothering you. Get a bit of wd-40 or gt-85 on there to keep some moisture off and clean and re-lube the rest of the drivetrain. – Chris Jun 23 '17 at 19:23
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Sorry, those chainrings are riveted in place. You just have to replace the whole crank arm.

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    And if you are going to replace it, you'll want to take the old one into a shop to make sure the new one is compatible. The main difference I'm thinking of is how far left or right the rings are in comparison to the crank. Otherwise you may need to get a different length bottom bracket to position the rings properly. – Noah Sutherland Jun 22 '17 at 21:17
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    Noted. It really isn't worth the bother with this bike, though. – Alex Jun 22 '17 at 23:47
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You could drill out the rivets (and later replace them with button-head hex screws) so that you could take off the chainrings. But this would be more effort than its worth. And it's not like you could easily find replacement chainrings anyway.

As @criggie notes, there's not nearly enough rust to make this worth it. Scrubbing the chainrings with chain cleaner and a brush should take off most of it. Those 'rust' marks are places where the chain abrades when the gears shift, any paint you put on them will be scraped off the next time you shift.

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